Narrative devices in TV shows

I like Fringe.  For me it was a bit of a slow-burner, but transpired to be excellent.  It bears some similarities to X-Files, and employs some clever devices which work well to drive the narrative.  Its some of these, and devices used in other shows, which I'm going to explore here:

Please be aware, this post contains spoilers!

1) John Scott's memories.

It is revealed early on in season one of Fringe, that Agent Olivia Dunham has absorbed some of the memories of her former lover, and FBI partner, John Scott.  I won't spoil how this came about but what transpires is a wonderful device the writers can utilise on a whim to drive the plot forward:  anything Dunham looks at may trigger a memory of John Scott's.  Thus, without knowing why, she may have a feeling or an association with a particular event, person, place etc.  This is utilised several times in the first season to great effect.  And essentially acts like a 'gut feeling' with some concrete foundation.  The genius comes into play because the writers can pick it up and drop it as a tool, as they see fit.  Thus if they get to a sticky point in any particular narrative they can simply play the "Dunham recalls a John Scott memory" card.  In fact, it is a similar device, and allows me to segue nicely on to...

2) Walter Bishop's 'insanity'.

Walter Bishop is a savant.  A genius so genius he is a genius in multiple fields. This sets up a nice device for the writers to use.  Fundamentally, Walter is an extremely useful character able to solve the vast majority of scientific dilemmas the characters face in the show.  However, in order to control the output of these solutions, the writers cleverly make the Walter Bishop character pretty flaky.  His 'insanity' means that sometimes he's off in a world of his own, which means just when they need him to utilise his genius to solve a particular issue, he can't always be relied upon, and is away with the fairies.  This creates for tension when tension is needed, and solutions when solutions are needed.

The counterpoint to 2) is how the Heroes TV series was nearly hoist by its own petard. In season one of that show, Peter Petrelli discovers he is an empath.  In the mythology of that show this means he can absorb other people's powers, just by standing near them.  This creates for a potential narrative blackhole, which I described to a bunch of friends over a meal one night.  The trouble is, if Peter has half an ounce of brains, he could (towards the end of the first season) teleport himself to Molly Walker (the little girl with the power to locate anyone).  He then absorbs her power automatically, and then can target anyone in the world with a power, teleport to their location, absorb their power, rinse and repeat.  Pretty quickly Peter would become godlike in his ability, and Sylar, and indeed anyone else wouldn't be able to stop him.

This is a pretty good example of the dangers of writers writing themselves into a hole.  Only really happens with writers dealing with fantastic subject matters like special powers, mind.

The way Heroes writers got round this problem was to have Peter stripped of all his abilities, and when he regains his empathy, have it limited to one power at a time.  i.e. he has to ditch his current power to take on a new one.